Electro-mechanical apparatus



Aug. 8, 1967 R. J. MORAN ETAL 3,334,585

ELECTED-MECHANICAL APPARATUS Filed June 22, 1964 2 Sheets-Sheet l I4 ,IO 23 IF I s. 1 20 l l X x I j IN VENTORS.

ROBERT J. MORAN DAVID W. BERNARD ATTORNEY.

Aug. 8, 1967 Filed June 22, 1964 R. J. MORAN ETAL ELECTRO-MECHANICAL APPARATUS 2 Sheets-Sheet 2 IFIGZ I N VEN TORS. ROBERT J. MORAN DAVID W. BERNARD BY {E2 44'- ATTORNEY.

3,334,585 Patented Aug. 8, 1967 fire 3,334,585 ELECTRO-MECHANICAL APPARATUS Robert J. Moran, Littleton, Mass, and David W. Bernard, Norwalk, Conn, assignors to Honeywell Inc.,

Minneapolis, Minn, a corporation of Delaware Filed June 22, 1964, Ser. No. 376,630 6 Claims. (Cl. 101-336) The present invention relates in general to web transports, and in particular to ribbon transports for highspeed printers.

The function of an inked ribbon in a printer is to effect printing on a paper web when a print hammer drives the paper web and the ribbon joint-1y against a platen. Either the platen or the print hammer may carry the type character to be printed. In high-speed printers a moving type carrier is generally used, which presents successive type characters to the print station at which the print hammers are located. In one such high-speed printer, the type car-- rier constitutes a constantly rotating print roll with up to 132 identical columns of characters around the periphery arranged to form rows of identical characters, some or all of which may be struck simultaneously by corresponding print hammers as each row of characters passes the print station.

In order to expose different ribbon areas to the print hammers and to prevent excessive ribbon wear, the inked ribbon must be moved past the print station. When the extreme ribbon positions are reached, a ribbon reversal is effected and the ribbon is moved past the print station in the opposite direction.

In general, any ribbon reversing mechanism requires means for sensing the end of the ribbon. The sensing device may produce a mechanical action for directly reversing the ribbon movement, or for generating an electrical signal which effects the ribbon reversal. Alter natively an electrical or other signal may be generated directly, which is then employed to effect the aforesaid ribbon reversal.

Various ribbon reversing devices for effecting such operation are in use in prior art printers. In one such device, the ribbon leaders, i.e. the terminal portions of the ribbon, have thickened areas which, when the ribbon moves to its extreme position, serve to actuate a microswitch positioned in close proximity to the ribbon. If a pair of ribbon motors is employed for moving the ribbon in mutually opposite. directions, the actuation of the microswitch may be employed to establish a circuit for energizing the idle ribbon-moving motor and for de-energizing the active motor. An undesirable feature of the aforesaid technique is the fact that the microswitch must be positioned in close proximity to the ribbon. Ribbon and paper dust may cause suflicient ribbon build-up to inadvertently actuate the microswitch before the extreme ribbon positions are reached. By coating the microswitch contacts, such dust may also produce a failure of the switch itself. Finally, the thickened ribbon leader areas may interfere with the proper spooling of the ribbon.

In another arrangement, an arm rides in contact with the ribbon both of whose leaders have slots cut therein.

When the ribbon reaches an extreme position, the arm drops through the slot and actuates a microswitch. The objectionable features of such a device are similar to those discussed above. In addition, opportunities are presented for jamming the movement of the aforesaid arm.

Still another technique employs a transparent portion in each ribbon leader, or a hole, through which a light beam actuates a photocell in the extreme ribbon position. The photocell, in turn, produces the requisite actuating signal. This technique is superior to those discussed above insofar as the relays may be located at a remote location where their operation is not affected by dirt and dust created by the ribbon and paper web. However, the operation is still subject to error. For example, a film of ink may gradually build up on the transparent Window of the ribbon leader to interfere with the operation of the photocell. The photocell itself may become coated where only a hole in the ribbon is used. Moreover, since a light source and a photocell are required, this technique is relatively expensive to implement.

It is accordingly the primary object of the present invention to provide a ribbon reversing mechanism which overcomes the foregoing disadvantages.

It is another object of the present invention to provide a ribbon reversing mechanism wherein the end of the ribbon is sensed electrically and the actuating relays are positioned at a remote location.

It is a further object of the present invention to provide a ribbon reversing mechanism whose sensing means are self-cleaning due to the action of the ribbon itself.

The foregoing objects of the present invention, together with features and advantages thereof, will become apparent from the following specification, when read in conjunction with the accompanying drawings in which:

FIGURE 1 illustrates a preferred embodiment of the present invention;

FIGURE 2 illustrates in detail certain features of the present invention; and

FIGURE 3 illustrates a preferred control circuit which may be used with the apparatus of FIGURE 1.

With reference now to the drawings, FIGURE 1 is a schematic representation of a preferred embodiment of the invention. A print roll 10 having raised characters on its periphery, is adapted to rotate in the direction of the arrow shown, to move successive data. characters past a print station 11. The latter includes a plurality of print hammers 12, one facing each column of characters on the print roll 10. In a preferred embodiment, up to 132 print hammers may be employed, aligned side by side. The print roll 10 is partly enclosed by a housing 14, which contains an opening 16 opposite the print station 11. A paper web 18 and a ribbon 20 are positioned between the print roll 10 and the print station 11. The ribbon Z0 terminates in a pair of ribbon leaders 21, consisting of Mylar or the like, only one of which is shown in FIGURE 1. Each leader is aflixed to the ribbon and further includes a conductive foil 23 glued thereto in a position to face the housing 14.

Printing is carried out in conventional manner. If a data character is to appear in a particular print line, all the print hammers 12 corresponding to the print positions wherein the character is to be printed, are simultaneously actuated when the character row which contains the desired characters is at the print station. The actuated hammers drive the paper web 18 and the ribbon 20 against the print roll 10 through the opening 16 to effect printing on the paper web.

As previously explained, in order to prolong the life of the ribbon 20 the latter is successively moved past the opening 16, to expose different ribbon portions to the print hammers. The ribbon transport for moving the ribbon comprises a pair of motors 22 and 24 and the associated ribbon spools 26 and 28 respectively, which are coupled to the aforesaid motors and which are adapted to rotate in the direction shown by the arrows in the drawing. Only one motor at a time is energized, the ribbon spool coupled to the other motor acting as a drag brake during this period in order to create tension in the ribbon 20. Specifically, the spool 26 includes a hub 30 looped by a friction band 34, having one end anchored to a fixed point and the other end coupled to a yielding tension spring 38. Similarly, the spool 28 contains a hub 32 looped by. a friction band 36 Whose ends are coupled to a fixed point and to the spring 33 respectively.

When the motor 22 is energized, the ribbon spool 26 turns in the direction of the arrow shown thereon, so that the friction band 34 pulls against the yielding spring 38. As the ribbon is coiled onto the spool 26, it unwinds from the spool 28 which will rotate in a direction opposite to that of the arrow shown thereon. As a consequence, the friction band 36 pulls against its fixed end so that a drag force is applied to the hub 32 and hence to the spool 28, which serves to maintain the ribbon 20 under tension. The opposite situation is true when the motor 24 is energized. In the latter case, the friction band 36 pulls against the yielding tension spring 38, while the friction band 34 pulls against its fixed end to apply a drag to the spool 26.

The housing 14 is positioned to act as a guide so as to determine, in part, the path of the ribbon 20. The housing 14 includes a pair of substantially identical insulators 40 and 45, which may consist of Teflon or the like, positioned on opposite sides of the opening 16. The insulator 40 carries a pair of contact terminals 42 in the form of a pair of conductive brass bars of substantially semicircular cross-section. The bars 42 are positioned transversely in the path of the ribbon 24) to make wiping contact with the latter during the movement of the ribbon. Likewise, the insulator 45 carries a pair of contact terminals 43, substantially identical to the contact terminals 42, and similarly positioned in the ribbon path.

FIGURE 2 illustrates in greater detail the aforesaid features with reference to one pair of contact terminals, applicable reference numerals having been carried forward. An insulator 44 in the form of a bar having substantially the same cross-section as the brass bars 42, is positioned between the latter. Each conductive bar 42 is thus insulated from the housing by the insulator 40, as well as from the other bar by the insulator 44. The contact terminals 42 are adapted to be energized from a pair of terminations 46 soldered to the contact terminals.

The ribbon leader 21 is joined to the ribbon 20 in the overlapping area shown, by glueing or the like. The foil 23 constitutes a strip of conductive material such as copper, so positioned that, as the ribbon 20 moves in the direction of the arrow shown, the foil bridges the contact terminals 42 to short out the insulator 44. The tension maintained in the ribbon 20 is responsible for good electrical contact between the foil 23 and the contact terminals 42. The latter are kept free of dirt by the wiping action, in both directions, of the ribbon 2tl.

FIGURE 3 illustrates a preferred embodiment of a control circuit which may be employed with the apparatus of FIGURE 1. Applicable reference numerals have again been retained. A pair of relays R1 and R2 are connected in series circuit with a DC source and with the pairs of contact terminals 42 and 43 respectively. The relay R2 has a single set of contacts R21. It is shown in its normal position in FIGURE 3, whence it couples the relay R1 to ground to complete an energizing circuit therefor through the DC source. The relay R1 has a first set of contacts R11 which are shown in their actuated position and which are adapted to couple the relay R2 to the aforesaid set of contacts R2-1 in their normal position. The relay R1 includes a second set of contacts R12, jointly actuated with the set of contacts R]l1 as indicated by the broken-line mechanical connection therebetween, and adapted to couple one of the motors 22 and 24 to an AC power source.

In operation, the energization of the relays R1 and R2 is mutually exclusive. In the mode of operation shown in FIGURE 3, a completed energization circuit exists for the relay R1 in the normal position of the set of contacts R2-1 which connect the relay R1 to ground. With the relay R1 energized, the contacts R11 are in their actuated position so as to break the connection between the relay R2 and the set of contacts R21. Similarly, the contacts R1-2 are in their actuated position, whence the motor 22 is energized from the AC source.

Assuming the prevailing direction of ribbon movement to be that shown by the arrow in FIGURE 2, the conductive strip 23 approaches the contact terminals 42 in one extreme ribbon position. When contact is established, the intermediate insulating bar 44 is shorted out and an energization circuit for the relay R2 is established between the DC source and ground. In response, the set of contacts R21 are actuated, causing the energization circuit of the relay R1 to open. The contacts R1-2 then switch to their normal position in which AC power is supplied to the motor 24 and the direction of ribbon movement is reversed. Simultaneously, the contacts R1-1 assume their normal position to establish an energization circuit for the relay R2 by way of the DC source, the relay coil, the contacts Rl-l and the contacts R21 to ground. The latter circuit maintains the relay R2 in its energized state when the conductive strip 23, which is only momentarily in contact with the contact terminals 42, moves off the latter owing to the reversal of movement of the ribbon.

The ribbon continues to move in the opposite direction until the other extreme ribbon position is reached when the conductive strip on the other ribbon leader bridges the contact terminals 43 to establish an energization circuit for the relay R1. The set of contacts R1-2 is actuated to switch power to the motor 22, thereby reversing the direction of ribbon movement. Simultaneously, the contacts R11 open to interrupt the energization circuit of the relay R2. The contacts R2-1 then assume their normal position, in which an energization circuit is established for the relay R1 which is maintained after the bridging conductive strip moves away from the contact terminals 43 upon the reversal of the ribbon.

Among the salient advantages of the present invention is the ability to locate the relays remote from the ribbon and paper. By thus shielding them from dust, the reliability of operation is enhanced. Only the contact terminals 42 and 43 are in contact with the ribbon. Owing to the wiping action of the latter in both directions, the contact terminals are kept clean to permit electrical contact with the conductive foil on the ribbon leaders. It will also be clear that the present invention provides a simple and economical ribbon reversal mechanism which requires only an inexpensive adaptation of the existing print roll housing and of the ribbon leader.

The invention is not limited to the illustrated embodiment and may find employment in various applications. It is readily applicable to different printers and different ribbon transports. For example, while the print roll housing is conveniently used as a ribbon guide to determine the ribbon path in the preferred embodiment illustrated in FIGURE 1, it will be clear that separate ribbon guides with contact terminals may be employed. Similarly, the ribbon housing itself, or the print roll if the ribbon contacts the latter, may be employed to establish the desired electrical contact with a conductive area of the ribbon. The ribbon transport is not limited to the arrangement shown but may, for example, use a pair of counter-rotating motors whose relative energization is varied depending upon the direction in which it is desired to move the ribbon. Alternatively, a single reversible motor may be used. The ribbon leader itself need not carry a separate strip of conductive foil. For example, it may consist of a material, such as aluminized Mylar, which is conductive throughout.

It will be apparent from the foregoing disclosure of the invention that numerous modifications, changes and equivalents will now occur to those skilled in the art, all of which fall within the true spirit and scope contemplated by the invention.

What is claimed is:

1. In an on-the-fly printer wherein print hammers aligned at a print station selectively drive a paper web and an inked ribbon against a rotating print roll to effect printing on said paper, a housing partly surrounding said print roll and substantially concentric therewith, said housing having an opening opposite said print station to admit said hammers, a ribbon transport adapted to move said ribbon under predetermined tension in mutually opposite directions past said opening in a path a portion of which is determined by said housing, two pairs of spaced contact terminals supported on opposite sides of said opening and electrically insulated from said housing, each pair of said spaced contact terminals substantially spanning the full width of said ribbon and protruding into the prevailing ribbon path, said ribbon path being locally distorted around the periphery of said contact terminals on a radius which is small relative to that of said housing, said tensioned ribbon, when moving, providing a wiping action on said contact terminals at a pressure substantially in excess of that exerted on said housing by said ribbon and suificient to maintain self-cleaning conditions on said contact terminals, said ribbon having a leader at each end including a portion of conductive material extending substantially the full ribbon width, each of said conductive portions being adapted to bridge a pair of said contact terminals upon moving opposite the latter so as to make positive electrical contact at said pressure and circuit means adapted to be activated when said terminals are bridged to reverse the prevailing direction of ribbon movement.

2. The apparatus of claim 1 wherein said circuit means include a first relay connected in series circuit with an energizing source and one of said terminal pairs and having first and second sets of contacts, a second relay connected in series circuit with said energizing source and the other terminal pair and having a third set of contacts, said first set of contacts being connected to said other terminal pair and being normally open, said third set of contacts being connected respectively to said first set of contacts and to said first relay and normally coupling the latter to ground, and a pair of motors adapted to move said ribbon in mutually opposite directions upon energization from a power source, said second set of contacts being connected to said motors and normally coupling one of them to said power source.

3. In an on-the-fiy printer, a print station including a plurality of aligned print hammers, a print roll having raised characters adapted to rotate past said print station, a housing enclosing said print roll and substantially concentric therewith, said housing including an opening opposite said print station, a paper web and an inked ribbon positioned between said print station and said print roll and adapted to be driven against the latter by said print hammers to effect printing on said paper web, said ribbon terminating in pair of ribbon leaders each including a portion of conductive material extending substantially the full ribbon width, a ribbon transport including a pair of motors adapted to move said ribbon under predetermined tension in mutually opposite directions past said opening through a path a portion of which is determined by said housing, two pairs of spaced contact bars supported on opposite sides of said opening and electrically insulated from said housing, each pair of said spaced contact bars substantially spanning the full width of said ribbon, each of said bars having a substantially semicircular cross section with a radius which is small cornpared to that of said housing, the rounded periphery of said contact bars protruding into the prevailing ribbon path and locally distorting the latter around said periphery, said tensioned ribbon, when moving providing a wiping action on said contact bars at a pressure substantially in excess of that exerted on said housing by said ribbon and suificient to maintain self-cleaning conditions on said contact bars, said conductive portions being adapted to bridge said pairs of bars upon moving opposite the latter to make positive electrical contact at said pressure, and a control circuit adapted to be actuated when a pair of bars is bridged to reverse the enregization of said motors.

4. The apparatus of claim 3 wherein said control circuit comprises first and second relays mutually exclusively energized from a DC. source, said first relay being connected in series circuit with said D.C. source and one of said bar pairs and having first and second sets of contacts, said second relay being connected between said D.C. source and said other bar pair and having a third set of contacts, said first set of contacts being connected between said second relay and said third set of contacts and being normally open, said third set of contacts being further connected to said first relay and normally adapted to ground the latter, said second set for contacts being connected to both said motors, and normally adapted to energize one of them from a source of power.

5. In a high-speed printer of the type wherein a type carrier moves successive data characters past a print station, a housing partly enclosing said type carrier and substantially concentric therewith, a paper web and an inked ribbon movably positioned between said print station and said housing, said print station including hammer means adapted to drive said paper web and said ribbon against selected characters of said moving type carrier through an opening in said housing, a ribbon leader at each end of said ribbon including a strip of conductive material transverse to the direction of ribbon movement and extending substantially the full ribbon width, a ribbon transport including a pair of motors selectively adapted to move said ribbon under predetermined tension in mutually opposite directions through a path a portion of which is determined by said housing, a pair of spaced, aligned, conductive bars positioned on each side of said opening of said housing and electrically insulated from the latter, one bar of each of said pairs being coupled to ground, the other bar of each pair being coupled to a DC. source, each pair of said spaced conductive bars substantially spanning the full width of said ribbon and protruding into the prevailing ribbon path, said ribbon path being locally distorted around the periphery of said conductive bars on a radius which is small relatvie to that of said housing, said tensioned ribbon, when moving, providing a wiping action on said conductive bars at a pressure substantially in excess of that exerted on said housing by said ribbon and sufiicient to maintain self-cleaning conditions on said conductive bars, and relay means connected to said motors, said relay means being further connected to said conductive bars and being adapted to energize one or the other of said pair of motors in accordance with which pair of bars is shorted together upon the arrival of a conductive ribbon leader strip establishing positive electrical contact at said pressure.

6. In a high-speed printer of the type wherein a type carrier moves successive data characters past a print station to efiect selective printing on an intermediately positioned paper web, a housing partly enclosing said type carrier and substantially concentric therewith, said housing including an opening opposite said print station, an inked ribbon movably positioned between said and said paper web and having a portion of its path determined in part by said housing, a ribbon leader at each end of said ribbon including a transverse strip of conductive material etxending substantially the full ribbon width, a ribbon transport including a pair of motors adapted to move said ribbon under predetermined tension in mutually opposite directions, first and second pairs of spaced, aligned, conductive bars carried by said housing transverse to the direction of ribbon movement on opposite sides of said opening, each pair of said spaced bars substantially spanning the full width of said ribbon, said bars being insulated and protruding outward from said housing into the prevailing ribbon path, said ribbon path being locally distorted around the periphery of said bars on a radius which is small relative to said housing, said tensioned ribbon, when moving, providing a wiping action on said bars at a pressure substantially in excess of that exerted on said housing by said ribbon and sufiicient to maintain self-cleaning conditions on said bars, a first relay coupled in series with a DC. source and said first pair of bars and having first and second sets of contacts, a second relay coupled in series with said D.C. source and said second pair of bars and having a third set of contacts connected respectively to said first relay and to said first set of contacts normally coupling said second relay, said third set of contacts being normally adapted to energize said first relay from said D.C source, each of said a relays being adapted to be energized through its connected pair of spaced bars when the latter are bridged upon the arrival of one of said conductive leader strips establishing positive electrical contact at said pressure, said last recited energization of a relay terminating the prevailing energization of the other -relay to reverse the direction of ribbon movement.

References Cited UNITED STATES PATENTS 5/1940 Carroll 22624 X 5/ 1946 Wells et a1 226-33 4/1955 Lekas 226-50 X 1/1958 Garwood et al. 197-489 X 1/1963 Paige 101-93 11/1964 Dubin 101100 X 5/1965 Pensavecchia et a1. 10196 FOREIGN PATENTS 2/ 1931 Germany.

ROBERT E. PULFREY, Primary Examiner.

P. R. WOODS, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,334 ,585 August 8 1967 Robert J. Moran et al It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 5, line 50, "in pair" should read in a pair Column 6 line 13, after "motors" cancel the comma; line 57 after "said", first occurrence, insert housing Column 7, line 10, cancel "a".

Signed and sealed this 24th day of February 1970.

(S EAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Attesting Officer Commissioner of Patents 

1. IN AN ON-THE-FLY PRINTER WHEREIN PRINT HAMMERS ALIGNED AT A PRINT STATION SELECTIVELY DRIVE A PAPER WEB AND A INKED RIBBON AGAINST A ROTATING PRINT ROLL TO EFFECT PRINTING ON SAID PAPER, A HOUSING PARTLH SURROUNDING SAID PRINT ROLL AND SUBSTANTIALLY CONCENTRIC THEREWITH, SAID HOUSING HAVING AN OPENING OPPOSITE SAID PRINT STATION TO ADMIT SAID HAMMERS, A RIBBON TRANSPORT ADAPTED TO MOVE SAID RIBBON UNDER PREDETERMINED TENSION IN MUTUALLY OPPOSITE DIRECTIONS PAST SAID OPENING IN A PATH A PORTION OF WHICH IS DETERMINED BY SAID HOUSING, TWO PAIRS OF SPACED CONTACT TERMINALS SUPPORTED ON OPPOSITE SIDES OF SAID OPENING AND ELECTRICALLY INSULATED FROM SAID HOUSING, EACH PAIR OF SAID SPACED CONTACT TERMINALS SUBSTANTIALLY SPANNING THE FULL WIDTH OF SAID RIBBON AND PROTRUDING INTO THE PREVAILING RIBBON PATHS, SAID RIBBON PATH BEING LOCALLY DISTORTED AROUND THE PERIPHERY OF SAID CONTACT TERMINALS ON A RADIUS WHICH IS SMALL RELATIVE TO THAT OF SAID HOUSING, SAID TENSIONED RIBBON, WHEN MOVING, PROVIDING A WIPING ACTION ON SAID CONTACT TERMINALS AT A PRESSURE SUBSTANTIALLY IN EXCESS OF THAT EXERTED ON SAID HOUSING BY SAID RIBBON AND SUFFICIENT TO MAINTAIN SELF-CLEANING CONDITIONS ON SAID CONTACT TERMINALS, SAID RIBBON HAVING A LEADER AT EACH END INCLUDING A PORTION OF CONDUCTIVE MATERIAL EX- 